if you're gonna buy a 4runner take comfort in knowing there are so many mods that can be done AND so much internet resources available for researching/help. you will spend hours researching and reading because you will be intrigued
make sure you know the differences in trim levels. there are lots of "how do I know if I have this" questions. the following link might be helpful. seems to have 20 years worth of 4runner brochures
Auto-Brochures.com|Toyota Car PDF Sales Brochure/Catalog/Flyer/Info 4Runner 86 Avalon Camry Celica, CH-R, Corolla Corona Echo FJ Cruiser Highlander Land Cruiser Mark II
Matrix Mirai MR2 Prius RAV4 Sequoia Sienna Solara Supra Tacoma Tundra Venza Yaris
never rush a purchase before you're comfortable but just know these vehicles can go FAST depending on where you live. I purchased mine 2 days after it was posted online from a dealer. I was actually the second person to purchase the vehicle, the first person couldn't get financing so I scooped it. test drive before you're ready to buy and then when you're ready be prepared to act fast when the right rig comes up. less of an issue if you buy new
price negotiations will be hard (or I just suck at them). dealers and savvy sellers know there's high demand. Instead of negotiating on price try and negotiate add ons (floor mats, cargo covers, touch up paint supplies, cargo equipment, roof racks, etc.). see what you can get thrown in. my dealer wouldn't budge on price but I got a bunch of accessories for a very low price with only a little off the sticker price
this is just a rule I follow because I'm no mechanic: always have full service history for the vehicle. 4runners are tanks, they last. but don't overlook the importance of a complete service history, especially if mileage is higher. I've called toyota dealers with a VIN and asked them to walk me through the complete service history and send it to me via email. they've never had an issue doing so